Fiber composite material

Abstract

The invention relates to a fiber composite material and to a method for producing same.

Description

[0001] SGL CARBON SE 2024 / 003 WO November 5, 2025

[0002] FIBER COMPOSITE MATERIAL

[0003] Subject matter of the invention

[0004] The invention relates to a fiber composite material and a method for its production.

[0005] Background of the invention

[0006] The production of automotive components from fiber-reinforced composite materials is well-established. However, for such components to be suitable for mass production, cost-effective and scalable manufacturing processes are needed, which are currently lacking.

[0007] GB-A 1485586 discloses the production of a unidirectional tape by discontinuously pressing layers of thermoplastic films and layers of parallel fiber bundles. However, a problem with this process is the insufficient impregnation of the individual fibers when the impregnation time is too short. Extending the impregnation time, however, leads to reduced throughput and thus lower profitability of the process. Furthermore, tape lamination generally results in an uneven matrix-to-fiber material distribution within the fiber composite.

[0008] EP3053734 B1 discloses a process in which a strand of reinforcing fibers impregnated with thermoplastic resin is hot-wound around a structure formed on a preforming tool to obtain a preform of the part to be manufactured. This preform is then cooled and removed from the preforming tool. Since the thermoplastic matrix material must be completely heated before processing, this process is also complex. Furthermore, the heating can cause the semi-finished product to swell, which further complicates the scaling of the process.

[0009] EP0383199A1 discloses a method for producing fiber-reinforced composites in which parallel fiber bundles and thermoplastic melt are continuously pressed together briefly in a double-belt press at a pressure of at least 10 bar, thereby embedding the fiber bundles in a matrix so that the individual filaments are completely wetted. Existing methods are therefore unable to produce fiber-reinforced composites of sufficient quality, or only at an insufficiently cost-effective rate.

[0010] TASK

[0011] Against this background, the object of the present invention was therefore to provide a fiber composite material that can be produced in a cost-effective and scalable manner and that has comparable or even better mechanical properties than materials known from the prior art.

[0012] Description of the invention

[0013] This problem is solved according to the invention by a fiber composite material, preferably for use as an automotive component or as a component of an automotive component, comprising

[0014] ■ a dry fiber material and

[0015] ■ mind, a force introduction element characterized in that the dry fiber material on the mind, a force introduction element, is encased with a fixing agent and at least 50%, preferably 70%, particularly preferably 80% of the filaments of the fiber material are displaceable relative to each other, or the fiber material on the mind, a force introduction element, is encased with a fixing agent and also the entire fiber composite material is at least partially encased with a fixing agent and at least 50%, preferably 70%, particularly preferably 80% of the filaments of the fiber material are displaceable relative to each other.

[0016] "Fiber materials" are materials that have or consist of linear, thread-like structures. In the fiber composite material according to the invention, the fiber material is present in the form of one or more layers, which partially, preferably completely, have or consist of long and / or continuous fibers aligned parallel along an axis of extension. Each fiber layer has its own axis of extension, whereby the axes of extension of the one or more layers can be identical, i.e., overlapping or parallel. Within the scope of the invention, "dry fiber material" is understood to mean that the filaments are displaceable relative to one another and have no supporting effect in the longitudinal direction. The dry fiber materials used can also have a sizing agent that does not prevent the individual filaments from being displaceable relative to one another.

[0017] Within the scope of the invention, "enveloping" means that, despite the enveloping fixing agent, at least 50%, preferably 70%, and particularly preferably 80% of the filaments of the fiber material are displaceable relative to one another. This compensates for unequal lengths of the fiber material, allowing a higher peak load to be transmitted under load. The "extension axis" defines the direction of the fiber layer along which the parallel-oriented long or continuous fibers, i.e., the linear structures made of fiber material, extend lengthwise. This corresponds to the direction of the greatest extension of the fibers, i.e., their longitudinal extent. Since the extension axis serves only to define the direction and determine the length LFI, L0F2, it represents the infinite number of parallel extension axes that theoretically exist. Its longitudinal extent is at least long enough that all fiber extensions in this direction, i.e.,the lengths LFI , LF2, etc., can be determined.

[0018] The length LFI, LF2, etc., over which the individual fibers extend along the respective extension axis EFLI, EFL2 of the respective layer, is, in the simplest case of an ideally linear arrangement of the fibers along or parallel to the extension axis, equal to the total fiber length itself. In the case of a non-linear arrangement of the fibers, for example, in the presence of bends, the corresponding length can be determined by projecting it onto the extension axis. The total fiber length, i.e., the length from the fiber start point to the fiber end point, is, for example, different from the length along the extension axis in designs with angled or curved layers, which are obtained, for instance, by winding around an angled or round forming body such as an eyelet.

[0019] The fiber composite material according to the invention comprises a fiber material selected from the group consisting of glass fibers, carbon fibers, ceramic fibers, basalt fibers, boron fibers, steel fibers, polymer fibers, or natural fibers or mixtures thereof, preferably polymer fibers such as aramid or nylon fibers, particularly preferably aramid fibers from the group of polymer fibers.

[0020] Polymer fibers are synthetic fibers such as aramid and nylon fibers. Natural fibers are fibers derived from natural sources such as plants, animals, or minerals and which can be used directly without further chemical conversion reactions. Examples according to the invention include flax or hemp fibers, as well as protein fibers or cotton. Regenerated fibers, i.e., fibers produced from naturally occurring, renewable raw materials via chemical processes, can also be used according to the invention. Such fiber materials are characterized by improved recyclability and thus particularly high sustainability. Carbon fibers are particularly preferred for protective devices in aircraft applications, especially due to their weight advantage and higher modulus of elasticity; glass fibers are particularly preferred in automotive applications.

[0021] In a further advantageous embodiment, the fiber material is designed as fiber strands or fiber ribbons present in at least one layer.

[0022] Within the scope of the invention, "layers" are understood to mean one or more layers of fiber strands or fiber tapes, wherein these are stacked on top of each other or are formed by one or more loops around, for example, an eyelet.

[0023] In the context of this invention, fiber strands are understood to be bundles of continuous or long fibers, whereby the number of filaments is not further limited. The number of layers depends on the performance to be achieved. The more layers, the more durable, but also the heavier the component.

[0024] And if present, the bending radius of the force application elements must be chosen to be as large as possible in order to keep the bending stresses due to the deflection low. For this to happen, the height of the individual layers must be reduced to a minimum.

[0025] Preferably, the number of individual fibers in one or more layers is > 3000, more preferably > 20,000, more preferably > 24,000, and most preferably > 48,000. This is particularly advantageous when using continuous fibers, i.e., filaments. By using a correspondingly high number (so-called "heavy tows"), the use of multiple individual rovings for producing a single fiber layer of the fiber composite material can be eliminated, i.e., the number of rovings required can be reduced. This allows for the use of smaller creels in the manufacturing process, making the process significantly simpler, more stable, and with higher output. Fiber composite materials with rovings of the high number of individual filaments described above are easier to process and therefore particularly cost-efficient.

[0026] Within the scope of the invention, "long fibers" are understood to mean fibers with a total fiber length L of 1 to 50 mm. The fibers of the fiber material according to the invention preferably have a total fiber length L where L > 25 mm, preferably L > 35 mm. Within the scope of the invention, "continuous fibers" are understood to mean fibers with a total fiber length L > 50 mm. The fibers of the fiber material according to the invention preferably have a total fiber length L where L > 75 mm, preferably L > 100 mm, even more preferably L > 1 m, and even more preferably L > 10 m, but preferably also < 50,000 m. The use of continuous fibers is preferred. This results in components with particularly advantageous mechanical properties.

[0027] According to the invention, the at least one force introduction element is selected to be made of metal, plastic or fiber-reinforced plastic.

[0028] In a further advantageous embodiment, the fixing agent is a plastic. The fixing agent serves to encase the fiber strands or fiber tapes at the at least one force application element. Preferably, the fiber strands or fiber tapes are locally encased by the fixing agent at the at least one force application element. Alternatively, complete encasement of the entire fiber composite material is also possible.

[0029] According to the invention, the plastic of the fixing agent is selected from the group consisting of thermoplastics, elastomers, or thermosets. Preferably, the fixing agent is made of a thermoplastic material to achieve high recyclability. Additionally, the addition of a filler can be advantageous to achieve even better performance of the fiber composite material.

[0030] In a further advantageous embodiment, the plastic of the fixing agent is selected from the group consisting of polyamides (PA), preferably PA6, PA 6,6, PA 4,6, polypropylene (PP), polyethylene (PE), polyesters such as polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polyoxymethylene (POM), polycarbonate (PC), polyethersulfone, polyetherketones, polyphenyl ethers (PEI), copolymers and / or mixtures of the aforementioned polymers, polyurethanes, particularly preferably of polypropylene, or polyamides, or epoxy resins or polyurethanes or phenolic resins.

[0031] In this context, polymer is understood to be a chemical substance that has more than 50 wt.%, preferably more than 70 wt.%, even more preferably more than 80 wt.%, even more preferably more than 90 wt.% and most preferably more than 95 wt.% macromolecules.

[0032] “Macromolecules” are molecules composed of one or more identical or similar structural units, the constitutional repeating units (IUPAC. Compendium of Chemical Terminology, 2nd ed. (the “Gold Book”), A.D. McNaught, A. Wilkinson, Blackwell Scientific Publications, Oxford (1997), S.J. Chalk. ISBN 0-9678550-9-8). Such macromolecules have more than 10 repeating units, preferably more than 15. The molar mass is preferably at least 3,000 g / mol, more preferably at least 5,000 g / mol, more preferably at least 7,000 g / mol, and most preferably at least 10,000 g / mol.

[0033] Polymers are typically produced by the polymerization reaction of monomers or oligomers, which possess one or more of the constitutional repeating units. An oligomer is defined as a molecule formed from several monomers and therefore composed of a multitude of structurally identical or similar structural units. Within the scope of the invention, the term oligomer is used when the molecule is produced from a reaction of 2-10, preferably 2-8, preferably 3-7 monomers.

[0034] The fiber composite material is often exposed to high mechanical loads in its intended use and therefore preferably has a particularly pronounced mechanical resistance and / or strength, which is provided in particular by the fiber layer(s).

[0035] In a preferred embodiment of the invention, one, several or all of the fiber layer(s) of the fiber composite material have a tensile strength along the axis of extension of the long or continuous fibers of at least 500 N / mm². 2 , preferably at least 1200 N / mm 2 , even more preferably at least 1600 N / mm 2 and preferably at least 2000 N / mm 2

[0036] Preferably, one, several or all fiber layers of the fiber composite material have a tensile strength along the axis of extension of the long or continuous fibers in the range of 500 N / mm². 2 up to 2000 N / mm 2 Below this range, the tensile strength is not sufficiently high for typical applications, such as in the automotive sector; above this range, the use of particularly complex fiber materials is necessary, which are also susceptible to shear forces acting perpendicular to the fiber.

[0037] The tensile strength can be determined as described in ISO 527.

[0038] In a further advantageous embodiment, the at least one force application element is an eyelet or a thimble. Particularly preferred is the production of a layered structure by winding around spaced-apart eyelets, as illustrated in detail in the experimental section. The ends of the fiber tapes present within the winding can be joined together, for example by thermal joining, to obtain a closed loop. However, this is often unnecessary with multiple windings, thus further simplifying the process. Partial wrapping of the eyelet(s) (preferably a maximum of 270°) is also preferred if a fiber tape or strand terminates at an eyelet. This is generally sufficient to secure the fiber tape or strand.The eyelets can remain in the fiber composite material according to the invention, for example to facilitate easy assembly; alternatively, a removable eyelet or an alternative wrapping device can be used. The invention preferably relates to a fiber composite material produced according to the inventive method, wherein the fiber composite material preferably has free, i.e., not connected, ends.

[0039] According to the invention, the fiber composite material is a pull cable for a front-end module of a passenger car.

[0040] The fiber composite material according to the invention is preferably a motor vehicle component, a building component, a composite part for an aircraft or spacecraft or a rail vehicle or a component thereof.

[0041] The fiber composite material is particularly preferably a motor vehicle component or a part thereof. In this case, the motor vehicle component formed by the fiber composite material, or of which the fiber composite material is a part, is preferably a tow cable for a front-end module of a passenger car. Further preferred motor vehicle components are selected from the group consisting of trunk floor panels, instrument panels, door and roof trim, stabilizers, rods, control arms, underbody protection components, structural components, cross members (behind the bumper), wheel housings, engine compartment components, brake and clutch linings and discs, sound insulation, thrust panels, and seals. The fiber composite material is particularly preferably a rod or a cable.

[0042] In a further preferred embodiment of the invention, the fiber composite material is a part of an aircraft or spacecraft, such as an airplane. Preferred parts in this context are tail rotor blades, main rotor hub plates, engine components, tanks, fuselage structures, fire protection elements such as fire-resistant coatings, rotating parts, turbine blades, and wings. In a further preferred embodiment of the invention, the fiber composite material is a structural component, for example, for a wind turbine. Preferred parts in this context are rotor blades for wind turbines, in particular the structural and outer skin components of the nacelle, cables and pipes, walls, and roofs.

[0043] A further object of the invention is a method for producing a fiber composite material comprising the following steps: a) providing a dry fiber material in the form of one or more fiber strands; b) providing at least one force introduction element; c) layering the one or more fiber strands, in particular by winding, onto or around the at least one force introduction element from step b); d) providing a fixing agent; e) fixing the fiber strands by means of the fixing agent from step d, preferably in a mold, by overmolding onto the at least one force introduction element from step c which is wrapped with fiber strands.

[0044] According to the invention, after or even during step e), the fiber composite material can additionally be overmolded at least partially with the fixing agent from step d).

[0045] The above steps are preferably carried out sequentially in the order a) - e), with the individual steps particularly preferably being carried out separately in time.

[0046] In the method according to the invention, at least 50%, preferably 70%, particularly preferably 80% of the filaments of the fiber material remain displaceable relative to each other, so that in the case of load the unequal lengths are first compensated and thus, at higher forces, all filaments absorb force simultaneously and thus the force acting on the individual filaments is lower.

[0047] The invention also relates to the use of the fiber composite material according to the invention as an automotive component or as a component of an automotive component.

[0048] The present invention is described below by way of example, using advantageous embodiments and with reference to the accompanying drawings. Brief description:

[0049] Fig. 1: schematically shows one step of the manufacturing process.

[0050] Fig. 2: schematically shows a fiber composite material according to the invention.

[0051] Fig. 3: shows a section of a fiber composite material according to the invention.

[0052] Fig. 4: shows a section of the fiber composite material according to the invention from Figure 3 under load.

[0053] Fig. 5: shows force / displacement diagrams for a prior art fiber composite material and a fiber composite material according to the invention.

[0054] Detailed description:

[0055] Figure 1 shows a partial step of the manufacturing process, in which dry fiber material (1) is wound around two spaced-apart eyelets (2). In a subsequent step (not shown), the eyelets (2) are coated with a fixing agent.

[0056] Figure 2 shows a section of a fiber composite material according to the invention. The eyelet (2) wrapped with fiber material (1) was encased with a fixing agent (2).

[0057] Figure 3 shows a section of a fiber composite material according to the invention. The eyelet (2) is wrapped with two layers of dry fiber material (1), whereby unequal lengths occur during the wrapping and the lower layer is wound more loosely.

[0058] Figure 4 shows a section of the fiber composite material according to the invention from Figure 3 under load; under load, the fibers shift relative to each other, so that the unequal lengths are balanced out.

[0059] Figure 5a shows a force / displacement diagram for a state-of-the-art fiber composite material in which fiber displacement is not possible because the fiber material is embedded in a matrix. Even under very low force applications, the first fibers begin to fail.

[0060] Figure 5b shows a force / displacement diagram for a fiber composite material according to the invention, in which delayed failure of the component occurs under the influence of force. The delayed failure is only made possible by the displacement of the fibers, caused by the lack of support in the longitudinal direction. The tensile force achieved is increased compared to a prior art fiber composite material.

[0061] EXAMPLES

[0062] The invention will now be described in more detail using an exemplary embodiment.

[0063] DESCRIPTION OF AN EXAMPLE OF EXECUTION

[0064] The fiber composite material according to the invention can be obtained by wrapping two spaced-apart eyelets with several fiber strands or fiber tapes. The manufacturing process is explained below by way of example.

[0065] To manufacture a suitable pull rope, two metal eyelets are provided and spaced according to the desired length of the pull rope (for example, 100 cm) and fixed at this distance. A strand of fiber (fiber material: carbon fiber, 24,000 filaments each) is wound around the spaced eyelets with a 45-fold winding, resulting in a layered structure as shown schematically in Fig. 1. Subsequently, in a further step, the eyelets are successively overmolded with approximately 10 g of PP GF 30 (polypropylene with a 30% glass fiber filling) for 30 minutes.

[0066] When overmolded with plastic, the carbon fibers are only partially encased. However, this does not negatively affect the maximum load-bearing capacity, as the force is introduced directly into the fiber by the force application element. Limited free movement is even advantageous, as it allows for the equalization of stress differences and ensures that multiple fibers are engaged simultaneously.

[0067] Such a pull cable can be used to meet the crash requirements in the front area of ​​a car. In a crash, the pull cable pulls the longitudinal beams inwards, thereby dissipating energy.

[0068] Reference symbol list

[0069] 1 Fiber material

[0070] 2 eyelets

[0071] 3 Fixatives

Claims

Patent claims 1. Fiber composite material, in particular for use as an automotive component or as a component of an automotive component, comprising ■ a dry fiber material and ■ mind, a force introduction element characterized in that the dry fiber material on the mind, a force introduction element, is encased with a fixing agent and at least 50%, preferably 70%, particularly preferably 80% of the filaments of the fiber material are displaceable relative to each other, or the fiber material on the mind, a force introduction element, is encased with a fixing agent and also the entire fiber composite material is at least partially encased with a fixing agent and at least 50%, preferably 70%, particularly preferably 80% of the filaments of the fiber material are displaceable relative to each other.

2. Fiber composite material according to claim 1, wherein the fiber material is selected from the group consisting of glass fibers, carbon fibers, ceramic fibers, basalt fibers, boron fibers, steel fibers, polymer fibers, or natural fibers or mixtures thereof, preferably polymer fibers such as aramid or nylon fibers, particularly preferably aramid fibers.

3. Fiber composite material according to claim 1 or 2, wherein the fiber material is formed as fiber strands or fiber ribbons present in at least one layer.

4. Fiber composite material according to any of the preceding claims, wherein the minimum is a force introduction element made of metal, plastic or fiber composite plastic.

5. Fiber composite material according to one of the preceding claims, wherein the fixing agent is a plastic.

6. Fiber composite material according to claim 5, wherein the plastic is selected from the group consisting of thermoplastics, elastomers or thermosets.

7. Fiber composite material according to claim 6, wherein the plastic is from the group consisting of polyamides (PA), preferably PA6, PA 6,6, PA 4,6, polypropylene (PP), polyethylene (PE), polyesters such as polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polyoxymethylene (POM), polycarbonate (PC), polyethersulfone, polyetherketones, polyphenyl ethers (PEI), copolymers and / or mixtures of the aforementioned polymers, polyurethanes, particularly preferably of polypropylene (PP), or polyamides, or epoxy resins or polyurethanes or phenolic resins.

8. Fiber composite material according to one of the preceding claims, wherein the at least one force introduction element is an eyelet or a thimble.

9. Fiber composite material according to one of the preceding claims, wherein the fiber composite material is a pull cable for a front-end module of a passenger car.

10. A method for producing a fiber composite material comprising the following steps: a) Providing a fiber material in the form of one or more fiber strands; b) Providing at least one force introduction element; c) Layering the one or more fiber strands, in particular by winding, onto or around the at least one force introduction element from step b); d) Providing a fixing agent; e) Fixing the fiber strands by means of the fixing agent from step d, preferably in a mold, by overmolding onto the at least one force introduction element from step c which is wrapped with fiber strands.

11. Method according to claim 12, wherein after or also during step e) the fiber composite material is additionally overmolded at least partially with the fixing agent from step d).

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